Re: panic: Memory modified after free

From: Kris Kennaway <kris_at_obsecurity.org>
Date: Tue, 31 Jan 2006 16:45:22 -0500
On Tue, Jan 31, 2006 at 01:38:34PM -0800, Steve Kargl wrote:
> On Tue, Jan 31, 2006 at 04:33:32PM -0500, Kris Kennaway wrote:
> > On Tue, Jan 31, 2006 at 01:22:09PM -0800, Steve Kargl wrote:
> > > The system is a dual proc Tyan K8S Pro with 12 GB of memory.
> > > The kernel is UP.  This was recorded by hand. I have the crash dump.
> > > 
> > > Memory modified after free 0xffffff02505e0c00(504) val=deadc0dd _at_
> > > 0xffffff02505e0cd0
> > > 
> > > panic: Most recently used by DEVFS1
> > 
> > Set up memguard to watch this malloc type in order to obtain useful
> > debugging.
> > 
> 
> OK, I've read the memguard manpage and it says to add
> 
> vm.memguard.desc=<memory_type>
> 
> to /boot/loader.conf.  Where to I get info for what <memory_type>
> actually means?

Look at the relevant MALLOC_DEFINE() in the source, it's the second
field (see malloc(9)).  This should probably be clarified in the
memguard manpage.

Kris
Received on Tue Jan 31 2006 - 20:45:23 UTC

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